The present invention relates to fabric softener compositions, especially adapted for use in the rinse cycle of a laundering process and, in particular, the concentrated and ready-for-use aqueous fabric softener compositions which are stable at both low and high ambient temperatures, i.e. the compositions do not form a gel, and which are easily dispersible in water when used.
Compositions containing quaternary ammonium salts having at least one long chain hydrocarbyl group are commonly used to provide fabric softening benefits when employed in a laundry rinse operation; for example, see U.S. Pat. Nos. 3,349,033; 3,644,203; 3,946,115; 3,997,453; 4,073,735; 4,119,545; etc.
For most aqueous softener compositions containing cationic quaternary ammonium compounds or imidazolinium compounds as active ingredients, concentrations of such cationics has, in general, been limited to the range of about 3 to 6 or 7% by weight (see, e.g., U.S. Pat. No. 3,904,533 and U.S. Pat. No. 3,920,565). Such a low concentration is generally necessitated by the fact that cationics form gels in water systems at concentrations at above about 8%. While the use of electrolytes to lower the viscosity of such compositions is known (see, e.g. U.S. Pat. No. 4,199,545), such electrolytes are far from satisfactory. From a functional point of view, the electrolytes often do not perform as required, particularly at concentrations of the cationics in the neighborhood of about 12-15%. Further, while the performance of the electrolytes may mitigate some of the gelling problem, their use is far from satisfactory in providing a highly concentrated aqueous system of cationics which does not gel or severely change in viscosity within the usual range of temperatures encountered in the handling thereof, for example 0.degree. F. (about -18.degree. C.) up to about 140.degree. F. (about 60.degree. C.).
In U.S. Pat. No. 3,974,076, there is disclosed quaternary ammonium-containing softening composition of conventional cationic concentrations, i.e. about 3% to about 8%. These compositions are characterized by the very small particle size of the substantially water-insoluble quaternary ammonium softening compound, i.e. 90% by weight of the quaternary ammonium compound exists as particles which pass through a 1.2 micron filter. The components of the composition are present in the proportions of from about 2 parts to about 10 parts (preferably from about 3 to about 8 parts) by weight of the water dispersible quaternary ammonium compound; from about 0.1 to 2 parts by weight of the C.sub.8 to C.sub.20 fatty alcohol, with the weight ratio of quaternary compound to alcohol being in the range of from about 100:1 to about 5:1; from about 0.1% to about 2.0% by weight of a nonionic surfactant, the balance being a water-soluble liquid carrier.
In fact, the use of fatty alcohols as softening ingredients or as viscosity regulating agents in fabric softening compositions has been described elsewhere in the patent literature. For example, U.S. Pat. No. 4,213,867 to Cukier and Khan describes fabric conditioning compositions containing quaternary ammonium compounds and fatty alcohols or phosphoric acid esters thereof in admixture with a diluent; the compositions are pumpable at room temperature and are easily dispersed in water. These compositions are highly concentrated base mixes for subsequent dilution prior to distribution and use. The compositions generally contain between about 50 and 80% of quaternary ammonium compound, a diluent (C.sub.1 to C.sub.4 alkanol plus water) constituting between about 15 and 35% of the base mix and a third component in an amount of from about 5 to 25% which is a C.sub.18 to C.sub.28 fatty alcohol or a phosphoric acid ester thereof or mixtures thereof. The base mix is diluted with water to form an aqueous emulsion of 2-10% concentration based on the combined active ingredients, i.e. quaternary ammonium compound and fatty alcohol or phosphate ester.
U.S. Pat. No. 4,386,000 to Turner, et al describes a concentrated fabric softening composition containing a cationic softener and a viscosity control agent which is a combination of a first component, which is a noncyclic hydrocarbon, fatty acid, fatty acid ester, or fatty alcohol, with a water-soluble cationic polymer having an average molecular weight in the range of from about 2,000 to about 250,000. The water-insoluble cationic fabric softener is present in the composition in an amount of from 8% to 22% and the viscosity regulator system includes from about 0.5 to 6% of the first regulator component and from about 0.05 to about 1% of the water-soluble cationic polymer as the second regulator component.
The Turner, et al patent is stated to be an improvement over the Verbruggen European Patent Application No. 79200801.3 corresponding to Verbruggen U.S. Pat. No. 4,426,299. The Verbruggen patent discloses concentrated fabric softening compositions comprising water-insoluble cationic fabric softener and a viscosity control agent which may be a noncyclic hydrocarbon, a fatty acid, or ester thereof, or a fatty alcohol at a ratio of fabric softener to viscosity control agent of from 5:1 to 20:1. According to Turner, et al, these compositions are less effective as viscosity reducing agents and concentrated compositions at temperatures close to or above the Krafft point of the cationic softener.
European Patent Application No. 0086105 describes fabric softening compositions containing a cationic softener, lanolin and a viscosity control agent which may be an electrolyte, a polymer such as polyethylene glycol, a C.sub.12 -C.sub.40 hydrocarbon and halogen derivatives thereof, C.sub.9 -C.sub.24 fatty acids, fatty acid esters thereof, C.sub.10 -C.sub.18 fatty alcohols or water miscible solvents. The cationic softener's present in amounts of 0.5 to 30% by weight, the lanolin in amounts of from 0.25 to 40% by weight and, when the viscosity control agent is the fatty alcohol, it is present in amounts of 0.25 to 15% by weight. The aqueous medium comprises at least 25% of the composition and preferably at least 40% of the composition. However, none of the actual examples shown in this patent include fatty alcohol viscosity adjusting agent.
United Kingdom Patent Application GB No. 2,007,734A describes a fabric softener concentrate for subsequent dilution to the final concentration of active ingredients. The concentrate contains a fatty quaternary ammonium salt which contains at least one long chain alkyl group of 8 to 30 carbon atoms, and an oil or substantially water-insoluble compound having oily/fatty properties. The latter includes, among others, long chain fatty alcohols. Proportions of quaternary fabric softener to fatty alcohol compound of 1:9, 1:5, 4:6, 9:10 or 9:1 by weight are shown, generally with a lower alkanol alone or with an additional nonionic surfactant to provide liquid concentrate or diluted composition. The fabric softening compositions, i.e. the concentrates diluted with water, are described as including from 3 to 20% by weight of active ingredients. However, the actual examples only show amounts of active ingredients ranging from about 2.33 to 10% by weight.
French Patent No. 2,298,600 and corresponding German Patent No. 2,503,026 to Hoechst A.G. describe liquid aqueous preparations for laundry softening-rinsing agents, which include a germicidal agent. These preparations include a mixture of a quaternary ammonium salt cationic fabric softener and an alkyl imidazolinium compound fabric softener compound at a weight ratio of 2:1 to 1:2; about 1 to 6% by weight of a cationic disinfecting agent; about 0.5 to 5% by weight of a long chain fatty alcohol; about 0.1 to 5% by weight of a lower alkanol having about 1 to 3 carbon atoms; 0 to about 5% by weight of a nonionic emulsifier and the balance water, perfume, coloring matter and optical brighteners.
German DE No. 3,150,179-Al to Hoechst A.G. relates to concentrated liquid premixtures of cationic fabric softeners with alkoxylated amines and an additional ingredient which may be a fatty alcohol. Example 3 of this patent shows a concentrate containing 40% of the cationic fabric softener, 45% oleyl alcohol and 15% alkoxylated amine. Example 5 shows a concentrate including 70% by weight of the cationic quaternary ammonium salt fabric softener, 20% isostearyl alcohol and 10% alkoxylated amine.
U.S. Pat. No. 3,644,203 to Lamberti, et al discloses a fabric softening composition which is a mixture of a (a) cationic fabric softener and (b) a complex of (i) C.sub.12 to C.sub.22 fatty alkanol or alkane diol and (ii) alkali metal alkyl (C.sub.12 to C.sub.18) sulfate at a ratio of (a):(b) between 1.4:1 and 10:1 and a molar ratio (i):(ii) between 1:1 and 1:2.
While satisfactory results may be obtained with one or more of these prior art fabric softener compositions still further improvements are desired in terms of softening performance, ease of handling, storage stability, dispersibility in cold water, and overall cost effectiveness. In addition, it is desireable to provide improved fabric softening compositions which do not require or include such additional non-softening components as present in many of these prior art formulations, e.g. nonionic surfactant, lower alcohol cosolvents, cationic polymers, etc.